Interlocking Sewer Lid Lash Cap System is step up from the "normal" style of keeper and lash cap. The Sewer Lid provides 30% more surface area than a normal lash cap giving your valvetrain the stability and security it needs to remain intact in high-revving, tire spinning scenarios. It is used by the top engine builders and racers for piece of mind and virtually eliminates the possibility of a keeper or lash cap coming off during running of the engine.